nostr:npub1sc5xy5s4lks7tuehyzpvvvrqxh9j8srpu0f3cvuevh8plyrwpsfqcm4hj4

Cisco MLSpp: It's an undocumented library… for uuhh… Cisco Webex maybe? Meaning proprietary in practice.

OpenMLS: Also a library

BouncyCastle: This is basically OpenSSL for Java… and it's only in a branch of a fork.

BouncyCastle ticket actually made me found [url=https://www.ringcentral.com/us/en/blog/ringcentral-update-e2ee-2022/]RingCentral[/url] which is also proprietary.